The present invention relates to a cylinder for printing presses in which the interior of the cylinder, and possibly the cylinder barrel is at least partially filled with, or made of a metal foam.
Rollers and cylinders of different dimensions for printing presses are known which, because of the material used for them, have a large dead weight.
This is disadvantageous not only from the viewpoint of the large expenditure of material, but also because of the required large outlay in energy and time in the course of accelerating and braking the rotating rollers or cylinders.
It is furthermore known, particularly in connection with slim cylinders, for example plate cylinders, that the so-called xe2x80x9cchannel beatxe2x80x9d or xe2x80x9cchannel dropxe2x80x9d excites oscillations in the radial direction, which, among other things, can lead to irregularities in the drive, as well as to oscillation bands and loss of printed characters in the printed product.
For example, in accordance with DE-OS 30 12 060, cylinders for printing presses which are immune to oscillations are known. These cylinders are put together from several pieces and in which materials of different physical properties are used for oscillation damping.
DE 44 26 627 A1 describes a metallic composite material with a core of a porous metallic material.
U.S. Pat. No. 4,341,157 discloses a cylinder for a printing press. This cylinder has hollow spaces which, for the purposes of weight reduction and oscillation damping, while at the same time maintaining its strength, are filled with a damping material.
It is the object of the present invention to create a cylinder for rotary printing presses.
In accordance with the present invention, this object is attained by providing a cylinder with a tube-shaped outer jacket whose interior is at least partially filled with a metal foam. Alternatively, the cylinder barrel can be made of a metal foam.
The advantages which can be achieved by means of the present invention reside, in particular, in that the rollers or cylinders have a reduced weight, along with simultaneously reduced bending, as well as oscillation-damping properties. A satisfactory damping effect, for example in connection with channel beats, or channel drops, as well as a reduced weight are achieved by means of the presence of hollow spaces. Thus, rapid as well as energy-reduced acceleration or deceleration of the rollers or cylinders is made possible. In case of a web guide roller in particular, which is driven by the running paper web, an easily moving as well as slip-free drive is of advantage. Because of its reduced mass, the web guide roller is already driven slip-free by a running quarter-wide paper web.
In particular, the cylinder has good heat conducting properties because of the use of metal foam.
A rapid removal of the heat being created in the cylinders is made possible by the heat conducting properties of the metal- containing material.
In comparison with conventional cylinders, it is possible, by means of the use of metal foam, and with the same bending to reduce the weight, and therefore the moment of mass inertia.